Remove `time_t` from API (bug #61821). The bit-width of `time_t` might change depending on compile time switches. That can cause a mismatch between class declarations in public headers and the actual alignment of the compiled classes. Avoid that problem by not using `time_t` in (public) headers. * build-aux/mk-octave-config-h.sh, oct-conf-post.in.h: Define OCTAVE_TIME_T to `int64_t`. The type of `time_t` is not defined in the C/C++ standards. However in all(?) implementations, it's either a signed 32-bit or a signed 64-bit integer. Use a signed 64-bit integer for storing those values in Octave classes. * other files: Use OCTAVE_TIME_T instead of `time_t`. Don't include <ctime> in files where it's not needed.

--- a/libinterp/octave-value/ov-fcn.h	Thu Mar 10 18:58:29 2022 +0100
+++ b/libinterp/octave-value/ov-fcn.h	Sat Feb 26 13:46:48 2022 +0100
@@ -95,10 +95,10 @@
   virtual octave::symbol_scope scope (void) { return octave::symbol_scope (); }
 
   virtual octave::sys::time time_parsed (void) const
-  { return octave::sys::time (static_cast<time_t> (0)); }
+  { return octave::sys::time (static_cast<OCTAVE_TIME_T> (0)); }
 
   virtual octave::sys::time time_checked (void) const
-  { return octave::sys::time (static_cast<time_t> (0)); }
+  { return octave::sys::time (static_cast<OCTAVE_TIME_T> (0)); }
 
   virtual int call_depth (void) const { return 0; }